The present invention relates to methods and apparatus for handling both green timber and dried timber simultaneously.
As is well known, in the handling of timber lengths in a sawmill or the like, it is necessary to carry out operations such as sorting and trimming, drop-sorting by quality or size, and packaging of lengths of timber both in a green condition as well as in a dried condition.
During the development of the sawmill industry, a problem has come up in connection with how to mechanize the handling of sawed lengths of timber in sawmills which are of a small or medium size. The number of such sawmills, particularly in countries such as Finland and in the Scandinavian countries, is many times the number of large sawmills, but on the other hand experience has shown that it is prohibitively expensive for a medium sized sawmill to purchase every type of modern sawmill machinery which generally require separate machines and buildings therefor. These considerations are particularly true in the case of drop sorters, which are required in the sorting both of dried timber and green timber.
There are known machines and methods according to which the same machines may at different times be utilized to perform different operations, such as packaging of dry timber and packaging of green timber for kiln drying. In this connection reference may be made to Finnish Pat. No. 35,523.
However, all known prior art expedients have proved to be unable to provide a satisfactory solution as to the above problem, at least in connection with medium sized sawmills, where it is necessary to be able to perform simultaneously all of the operations in connection with dry as well as green timber lengths, so the problems of intermediate storage and the inconvenience resulting from different work shifts may be avoided.
Although, in theory, the number of pieces of sawed timber lengths to be processed in a sawmill is the same for green timber as well as for dried timber, experience has shown that in practice this is not true. Thus, the green timber lengths contain rejects which are partly eliminated prior to the drying process and additional pieces are lost due to damage thereof. Moreover, when handling timber of large dimensions, the sorting operations are slow, and this latter factor must be taken into consideration if it is desired to carry out sorting of the green and dried timber simultaneously.
It is necessary for such simultaneous operations to take into consideration both the capacity and the reliability in service of machines as well as human factors which may retard certain operations.